login password not accepted as a sodo password

[stevef]

If it is a keyboard layout problem have you tried checking what the key presses actually do when you are typing what you think is the correct password at the times when it doesn't work ?

I mean when in the terminal just type your password at the normal prompt and at the login screen select 'other user' and type in the password at the username prompt.  Do the same at a point where your password does work and compare.  If different it would suggest a keyboard setting problem which you can resolve by finding the right substitute keys.

There are password recovery guides on line - I've not tried any - otherwise a reinstall.